Chemical structure evolution and orientation selection in sol-gel-prepared ferroelectric Pb(Zr,Ti)O₃ thin films

We studied in detail the chemical structure evolution of Pb(Zr_1−x, Ti_x)O₃ (PZT) thin films on Pt electrodes during the initial thermal steps of their preparation using an alkoxide-based sol-gel process. Absorption-reflection Fourier transform infrared spectroscopy (AR-FTIRS) was used to monitor chemical reactions occurring in the films on a real temperature scale. We demonstrate that the chemical state of the pyrolyzed film strongly depends on pyrolysis conditions and can have a large effect on the orientation selection in the film. First, residual acetate groups, resulting from incomplete decomposition of the Pb acetate precursor, strengthen the (111) PZT texture component after crystallization. Second, OH bonds, which are seen to remain in the film after pyrolysis under specific conditions, are seen to strengthen the intensity of the PZT(100) reflection. Possible mechanisms behind these observations are discussed.